Wk12 - repro hormones Flashcards
(111 cards)
1
Q
Define the following term:
Gonadotropin.
Include examples in your answer.
A
Gonadotropins are hormones produced by the anterior pituitary, which act on the GONADS. At the gonads, they:
- Increase production of sex hormones.
- Stimulate production of sperm/ ova.
FSH and LH are gonadotropins.
2
Q
What stimulates gonadotropin hormone release, and where does this occur?
A
Gonadotropin-Releasing Hormone (GnRH) is produced in the hypothalamus, and stimulates gonadotropin release from the anterior pituitary.
3
Q
State the function of FSH in women.
A
FSH stimulates follicles of ovary to develop.
4
Q
State the function of FSH in men.
A
FSH stimulates sertoli cells, which facilitate sperm production.
5
Q
FSH and ___ combine in function to stimulate what?
A
FSH + LH combine to stimulate the secretion of oestrogens from the ovary (female).
6
Q
What inhibits FSH production, and where is such substance produced?
A
Peptide hormone inhibin; released by cells of the testes (sertoli)/ ovaries.
7
Q
State the function of LH in women.
A
- Stimulates ovulation.
2. Stimulates production of oestrogens/ progesterone within ovary.
8
Q
State the function of LH in men.
A
Stimulates production of androgens, by the testes (leydig or interstitial cells).
9
Q
What stimulates LH production, and where is such substance produced?
A
GnRH which is produced in the hypothalamus.
10
Q
What inhibits LH production?
A
Circulating levels of:
1. Oestrogens.
2. Progesterone.
3. Androgens.
note: this is negative feedback
11
Q
How does GnRH secretion occur; is it a steady flow, gradual build-up, or does it occur in pulses? (MALES)
A
GnRH secretion occurs in pulses; with interval around 60 - 90 minutes.
12
Q
What type of hormone is testosterone (is it a gonadotropin)?
A
Testosterone is an androgen not a gonadotropin; it’s release is triggered by gonadotropins.
13
Q
Describe the pulse frequency of gonadotropins in an adult male.
A
Pulse frequency of GnRH release is relatively STABLE in males. Consequently, plasma [] of gonadotropins/ testosterone remain within a narrow range.
14
Q
Most hormones released by the testes/ ovaries are (cholesterol/ peptide) based. This is with the exception of which hormone?
A
Most are cholesterol based, with exception of inhibin (which is peptide based).
15
Q
State the functions of testosterone in males. (4)
A
- Stimulates production of functional sperm.
- Maintains secretory glands.
- Stimulates development of secondary sex characteristics/ muscle growth.
- Influences metabolic reactions; induces aggression.
16
Q
Where, and from what is testosterone produced?
A
Testosterone is produced by the leydig (interstitial) cells of the testes. From either:
- Cholesterol.
- Acetyl CoA.
17
Q
How does testosterone travel in the blood?
A
Testosterone travels bound to either:
- Gonadal Binding Globulin (GBG).
- Albumens.
18
Q
Testosterone is a steroid hormone; does this mean it can pass through the cell membrane?
A
YES - steroid hormones are lipids and so they are lipophillic, and able to diffuse straight through the cell membrane.
19
Q
Where is the hormone receptor complex for testosterone?
A
DNA in the nucleus of the cell.
20
Q
In many tissues some of the testosterone is converted into a different compound. Name this.
A
Di-hydro-testosterone (DHT).
21
Q
DHT forms what ~% of the testosterone in circulation?
A
~10%.
22
Q
Some tissues are more sensitive to DHT - such as what?
A
Prostate gland.
23
Q
State the main stages of sperm development. (5)
A
- Spermatogonia.
- Primary spermocyte.
- Secondary spermocyte.
- Spermatid.
- Spermatozoa.
24
Q
State the supporting cells of sperm development.
A
Sertoli cells.
25
t/f: sertoli cells produce testosterone.
FALSE - leydig (interstitial) cells produce testosterone. Sertoli cells facilitate the differentiation and maturation of sperm cells.
26
Sertoli cells are a type of ______ cell.
Sustentacular cells.
27
What structure do sertoli cells help to form?
Blood - testes barrier.
28
What do sertoli cells secrete?
1. Inhibin - when FSH present.
| 2. Androgen binding protein (ABP) - into lumen of spermatic tube.
29
What does ABP do, post being secreted into the lumen of the spermatic tube by sertoli cells?
ABP binds to testosterone, making it:
1. Less lipophillic.
2. More concentrated.
30
The plasma of adult males contains small amounts of oestrogen.
a. ) Specifically, which oestrogen hormone?
b. ) What is the plasma [] of this?
c. ) What is the plasma [] of testosterone?
a. ) Oestradiol.
b. ) 2ng per decilitre.
c. ) 525ng per decilitre.
31
How is oestradiol formed? Include in your answer any relevant hormones.
1. 70% - from testosterone (converted by aromatase).
| 2. 30% - by sertoli and leydig cells.
32
t/f: sertoli cells produce fluid, and control release of sperm into the lumen.
True.
33
State the main hormone involved in the regulation of reproductive processes in women. How does it's secretion vary?
GnRH; it's secretion varies in both pulse frequency and amplitude.
34
What occurs, following a shift in the pulse frequency of GnRH?
Change of GnRH pulse frequency causes a change in pattern of FSH and LH secretion:
Frequency 1 - more FSH released.
Frequency 2 - more LH released.
(note: on graph, as GnRH frequency increases initially FSH drops and LH spikes)
35
What controls changes in the pulse frequency of GnRH?
Circulating levels of oestrogen and progesterone.
36
State the effect of OESRTOGEN on pulse frequency of GnRH.
Increases pulse frequency.
37
State the effect of PROGESTERONE on pulse frequency of GnRH.
Decreases pulse frequency.
38
State the RANGE of the uterine cycle.
24 - 35 days.
39
State the AVERAGE uterine cycle.
28 days.
40
State the phases of the uterine cycle. Include time lengths.
1. Menstrual phase: days 0 - 7.
2. Proliferative phase: days 7 - 14.
3. Post-ovulatory (secretory) phase: days 14 - 28.
(note: menstrual + proliferative = pre-ovulatory phase)
41
Name the arteries which penetrate the endometrium.
1. Spiral arteries.
| 2. Straight arteries.
42
Specifically, spiral arteries supply which layer of the endometrium?
Stratum functionalis.
43
Constriction of the spiral arteries (due to hormonal changes) induces which stage of the uterine cycle?
Menstrual phase.
44
Describe the occurrences seen due to the MENSTRUAL PHASE of the uterine cycle.
The menstrual phase of the uterine cycle is represented by the degeneration of the stratum functionalis, and consequent discharge of:
1. Blood.
2. Tissue fluid.
3. Mucous.
4. Epithelial cells.
45
Describe the occurrences seen due to the MENSTRUAL PHASE of the uterine cycle.
The menstrual phase of the uterine cycle is represented by the degeneration of the stratum functionalis, and consequent discharge of:
1. Blood.
2. Tissue fluid.
3. Mucous.
4. Epithelial cells.
46
The menstrual phase (uterine cycle) is caused by a sudden reduction in certain hormones. This reduction in hormones stimulates the uterus what substance? State the effect of this substance.
Uterus releases prostaglandins, which caused the vasoconstriction of endometrial blood vessels (spiral arteries constrict).
47
The menstrual phase (uterine cycle) is caused by a sudden reduction in certain hormones. This reduction in hormones stimulates the uterus what substance? State the effect of this substance.
Uterus releases prostaglandins, which caused the vasoconstriction of endometrial blood vessels (spiral arteries constrict).
48
Describe the occurrences seen during the PROLIFERATIVE PHASE of the uterine cycle.
1. Due to rising FSH + LH, newly-developing follicles of ovary secrete oestrogens.
2. Due to rising oestrogens, endometrium is stimulated to repair and grow. A new stratum functionalis forms and thickens, until the end of the phase.
49
Describe the occurrences seen during the SECRETORY PHASE of the uterine cycle.
Immediately post ovulation:
1. Corpus luteum is formed in ovary; this secretes LARGE amounts of oestrogen and progesterone.
2. Progesterone prepares the endometrium to recieve fertilised ovum (implantation):
a. ) Vascularisation of stratum functionalis.
b. ) Thickening of endometrium.
c. ) Epithelial cells store glycogen.
d. ) Increased quantity tissue fluid.
e. ) Increased secretory activity of endometrial glands.
50
What occurs in the uterus should fertilisation not take place?
1. Corpus luteum degenerates.
2. Rapid fall in oestrogen and progesterone.
3. Menses induced (cycle repeats).
51
State the phases of the ovarian cycle. Include time lengths.
1. Follicular phase (pre-ovulatory): 0 - 14.
| 2. Luteal phase (post-ovulatory): 14 - 28.
52
During early menses, follicles begin producing hormone(s) in response to increased levels of other hormone(s):
a. ) What hormone(s) stimulate the follicles to begin producing hormone(s)?
b. ) What hormone(s) do the developing follicles produce?
c. ) How many follicles begin this maturation process (in early menses)?
a. ) FSH + LH.
b. ) Oestrogens.
c. ) ~25.
53
At the beginning of menses ~25 follicles begin producing low amounts of oestrogens. How many follicles remain come the end of menses; and what have they developed into?
Of the ~25 follicles which began maturation at the onset of menses, ~20 will have developed into SECONDARY FOLLICLES come the end of menses.
54
What occurs to the ~19 other follicles which, come the latter part of the pre-ovulatory phase, do NOT develop into an ovum?
They undergo atresia (degenerate).
55
FSH and LH stimulate the follicles to produce oestrogens; what is the functional benefit of this?
The oestrogens produced by the follicles stimulate the thickening of the endometrium (s. functionalis).
56
What does the secondary follicle become before ovulation can occur (further stage of maturation)?
Graafian follicle.
57
Describe at what stage of the ovarian cycle FSH is greatest.
Mid pre-ovulatory phase.
58
Describe at what stage of the ovarian cycle LH is greatest.
End of pre-ovulatory phase.
59
State the hormone released by graafian follicles just prior to ovulation.
Progesterone.
| note: this may contribute to ovulation but main effector is definitely LH
60
State factor(s) which help to SWITCH OFF the FSH secreting cells of the anterior pituitary. During what phase does this occur?
FSH control (inhibition) occurs during follicular (pre-ovulatory) phase; due to:
1. Inhibin (from ovarian follicles).
2. Low progesterone levels (from ovarian follicles).
61
The LH surge which causes ovulation is a direct result of (negative/ positive) feedback, due to (high/ low) oestrogen levels.
Positive; high.
62
Oestrogens:
a. ) How many different oestrogens have been identified?
b. ) How many of these are significant; name them.
a. ) 6 identified.
b. ) 3 relevant:
1. B-oestradiol.
2. Oestrone.
3. Oestriol.
63
What are oestrogens synthesized from, and where does this occur?
Cholesterol or Acetyl CoA; in the ovary.
64
State the 3 main functions of oestrogens.
1. Development of endometrium, and secondary sexual characteristics.
2. Control fluid and electrolyte balance.
3. Increase protein anabolism (synergist to GH).
65
State the chemical reactions induced by THECA CELLS.
Cholesterol -> androstenedione.
| Androstenedione then diffuses to granulosa cells (adjacent).
66
State the chemical reactions induced by GRANULOSA CELLS.
Androstenedione -> estradiol, using AROMATASE ENZYME.
67
What stimulates the development of the corpus luteum (CL), post ovulation?
High levels of LH.
68
Briefly describe the process by which the CL is formed.
1. High levels LH.
2. Graafian follicle collapses, forming a blod clot within it known as CORPUS HAEMORRHAGICUM. This is reabsorbed by surrounding follicular cells.
3. Surrounding follicular cells enlarge, forming the CL.
69
During which days of the ovarian cycle does the CL form; and what is this phase known as?
15-28; the luteal phase.
70
t/f: FSH and LH continue to be secreted at high levels during the luteal phase.
FALSE - FSH and LH secretion is switched off by high oestrogen levels, which are high because of the corpus luteum's secretion.
71
State the predominant reason for FSH and LH levels dropping during the luteal phase.
As the corpus luteum develops, it secretes:
1. Oestrogens.
2. Progesterone.
3. Inhibin.
All of which (particularly OESTROGEN) exert negative feedback on the hypothalamus, reducing GnRH release and therefor FSH and LH release.
72
Which hormone is functionally dominant:
a. ) Oestrogen.
b. ) Progesterone.
B.
73
Late Luteal phase:
a. ) What occurs to the CL, should implantation NOT occur?
b. ) State the consequence of this in terms of hormonal levels, the uterine walls and cycle.
a. ) Atresia; it regresses to become the CORPUS ALBICANS.
b. ) Drop in oestrogen and progesterone, inducing:
1. Vasoconstriction of spiral arteries and the shedding of stratum functionalis. This induces new menstrual phase.
2. Stimulates hypothalamus to release GnRH, instigating new cycle.
(slide 20 inc all points)
74
State the 3 main functions of progesterone.
1. Prepares uterine walls for implantation.
2. Accelerates movement of oocyte/ embryo along the uterine tube.
3. Works in conjunction with other hormones to enlarge mammary glands.
75
What does high levels of progesterone inhibit? (2)
1. FSH and LH release (both at ant. pituitary and hypothal.)
| 2. Uterine contractions (labour).
76
What occurs to the CL if implantation does occur? Explain in detail, including the successor of the CL.
If implantation occurs then the CL is maintained, and over a period of 8-10 weeks it continues to secrete oestrogen and progesterone. At around this time, the CL regresses and the placenta takes over in it's job of oestrogen and progesterone secretion.
77
What hormone is responsible for maintaining the CL should implantation occur, and from where does this hormone originate?
Human Chorionic Gonadotropin (hCG), which is secreted from the placenta.
78
Which hormone is chiefly responsible for the mothers ability to maintain pregnancy, and how long into foetal development does it take for this hormone to reach sufficient amounts to do so?
Progesterone; after about ~7 weeks of development the placenta is producing enough progesterone to maintain pregnancy.
79
If implantation does occur:
| How many weeks into development does the CL last, before it regresses?
10 - 12 at max (starts to regress at weeks 8-10)
80
Expand the following acronym:
| hCG.
Human Chorionic Gonadotropin.
81
Expand the following acronym:
| hCS.
Human Chorionic Somatostatin.
82
State the function of hCG.
Maintains the CL, enabling it to continue to produce oestrogen and progesterone.
83
How long is hCG able to maintain the CL, and post the CL regressing does hCG secretion reduce?
hCG maintains the CL for 6-8 weeks. Post atresia of the CL hCG secretion continues (unknown why).
84
hCS is AKA as what?
HPL - human Placental Lactogen.
85
Where are hCG and hCS produced?
The placenta.
86
hCS:
a. ) Describe the trend in hCS secretion post fertilisation.
b. ) Describe the abundance pf hCS in the plasma, relative to other protein hormones.
a. ) 0-3 weeks nil, 3 weeks - last month of pregnancy rises steadily, last month reaches a plateau, then disappears from circulation before lactation begins.
b. ) 100x more prevalent then other peptide hormones.
87
hCS has a very (short/ long) half life.
Short.
88
State the function(s) of hCS.
1. Prolactin like effect: stimulates mammary glands to enlarge.
2. Diabetic effect:
a. ) Stimulate lipolysis (increasing FFA [])
b. ) Decrease maternal glucose uptake.
(note: hCS acts with maternal GH to produce the diabetic effect)
89
Why is it that hCS contributes toward successful pregnancy; what does it functions ultimately achieve?
Essentially the diabetic effect spares glucose for the developing foetus, this is why the mother is said to have 'gestational diabetes'.
90
Describe how PROGESTERONE secretion varies throughout pregnancy.
Increases steadily and steeply.
91
Describe how OESTROGEN secretion varies throughout pregnancy. How does this compare to PROGESTERONE secretion (which is greater)?
Increases steadily and steeply; OESTROGEN is greater.
92
In final months of pregnancy, the placenta is producing >___mg of progesterone.
250.
93
During pregnancy, what structure is the main producer of oestrogen?
Placenta.
94
Oestrogen is produced by the placenta during pregnancy; how does this benefit the developing foetus?
Promotes uterine blood flow to the foetus.
95
Why is the placenta considered an 'incomplete endocrine gland'?
Basically, the placenta supplies the cholesterol for the adrenal cortex of the foetus to convert it to estrogen.
Phil said:
"Placenta needs precursors to produce oestrogen and progesterone" but thats whack.
96
Which hormone inhibits uterine contractions?
Progesterone.
97
How long does pregnancy last (~)?
40 weeks.
98
Progesterone inhibits uterine contraction. So how is it labour can still take place?
Oestrogen levels overcome inhibitory effect of progesterone levels.
99
What non-hormonal substance released by the placenta may help to initiate contraction of the uterus?
Prostaglandins.
100
Which hormone, which is non-placental and non-ovarian, helps initiate contractions of the uterus?
Oxytocin.
101
What hormone is responsible for relaxing the symphysis pubis, and dilating the cervix?
Relaxin.
102
What stimulates oxytocin release?
Uterine wall stretch.
103
Why is the uterine muscle so responsive to oxytocin in the late stages of pregnancy?
Because there is an increase in the amount of oxytocin receptors during this time.
104
Other then stimulating uterine contraction, what other role does oxytocin play in relation to the uterine wall?
Prevention of haemorrhaging of uterine wall post placental expulsion.
105
State the function(s) of relaxin.
1. Dilates cervix.
2. Relaxes symphysis pubis.
3. Keeps uterus quiscent during pregnancy.
4. Aids development of mammary glands.
106
Prior to partuition, ~% of CO does the placenta receive?
~10%.
107
When is relaxin produced, and in what (relative) amounts?
Steadily produced throughout pregnancy, more is produced before childbirth.
108
Where is relaxin produced? (3)
1. CL.
2. Placenta.
3. Uterus.
109
Why does relaxin production cease post birth?
1. Placenta is expelled.
| 2. CL degenerated.
110
State the correct time frame for the following:
a. ) Until when does hCG maintain the CL?
b. ) When does the CL begin to degenerate?
c. ) When is the CL fully degenerated; ie. when does the placenta take over it's role?
a. ) 6-8 wks.
b. ) 8-10 wks.
c. ) 10-12 wks.
111
Explain what is meant by the following term(s):
| Gestational diabetes.
High maternal sugar levels, in effort to spare glucose for foetus.
